SONIX SN8P2308, User Manual

Page: 31 / 119

SN8P2318 Series
C-type LCD, RFC 8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 31
Version 1.5
2.2.6 Y, Z REGISTERS
The Y and Z registers are the 8-bit buffers. There are three major functions of these registers.

Can be used as general working registers

Can be used as RAM data pointers with @YZ register

Can be used as ROM data pointer with the MOVC instruction for look-up table
084H Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Y YBIT7 YBIT6 YBIT5 YBIT4 YBIT3 YBIT2 YBIT1 YBIT0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
After reset - - - - - - - -
083H Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Z ZBIT7 ZBIT6 ZBIT5 ZBIT4 ZBIT3 ZBIT2 ZBIT1 ZBIT0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
After reset - - - - - - - -

Example: Uses Y, Z register as the data pointer to access data in the RAM address 025H of bank0.
B0MOV Y, #00H ; To set RAM bank 0 for Y register
B0MOV Z, #25H ; To set location 25H for Z register
B0MOV A, @YZ ; To read a data into ACC

Example: Uses the Y, Z register as data pointer to clear the RAM data.
B0MOV Y, #0 ; Y = 0, bank 0
B0MOV Z, #07FH ; Z = 7FH, the last address of the data memory area
CLR_YZ_BUF:
CLR @YZ ; Clear @YZ to be zero
DECMS Z ; Z
– 1, if Z= 0, finish the routine
JMP CLR_YZ_BUF ; Not zero
CLR @YZ
END_CLR: ; End of clear general purpose data memory area of bank 0
…
2.2.7 R REGISTER
R register is an 8-bit buffer. There are two major functions of the register.

Can be used as working register

For store high-byte data of look-up table
(MOVC instruction executed, the high-byte data of specified ROM address will be stored in R register and the
low-byte data will be stored in ACC).
082H Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
R RBIT7 RBIT6 RBIT5 RBIT4 RBIT3 RBIT2 RBIT1 RBIT0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
After reset - - - - - - - -
 Note: Please refer to the “LOOK-UP TABLE DESCRIPTION” about R register look-up table application.